MATTER AND ENERGY. MIXTURES

UNIT 5

LESSON 1. MIXTURES

MATTER AND ENERGY

Salad is a mixture. It is made up of tomatoes, cheese, olives, lettuce and oil

A mixture is a physical combination of two or more substances. There are not any chemical reactions. It can be separated into different kinds of matter.

Water is a substance.

A substance is a particular kind of matter with uniform properties. It can not be separated into other kind of matter.

SUBSTANCES AND MIXTURES

In heterogeneous mixtures, we can appreciate the substances that make it up. In the picture, we can see different stones and sand.

In homogenous mixtures we cannot see different substances that make up the mixture. This vegetable soup is a homogenous mixture because we cannot differentiate among pumpking, potatoes or carrots.

HOMOGENEUS AND HETEROGENEUS MIXTURES

We can use different methods to separate the components of mixtures.The method we should use will depend on the characteristics of the mixture.We will see the most important methods.

SEPARATING MIXTURES

Some substances, like iron, are magnetics. We can separate some metals from non-magnetic substances using magnets. It is usefull, for example, for recovering metal from rubbish people throw away.

MAGNETIC SEPARATION

DECANTATION

We use it to separate liquids and solids and liquids with different densities. First, we have to wait until the solid forms a sediment at the bottom. Then we can pour off the liquid.

We use it to separate small particles from a liquid or a gas. A filter stops the particles but lets the gas or the liquid pass thought. A face mask uses filtration to avoid germs and some viruses.

FILTRATION

EVAPORATION

When we combine a solid and a liquid, we form a solution. We can separate them again by heating the liquid and becoming it a vapour, leaving the solid in the recipient. Salt is extracted from marine water using the sun heat. The water evaporates, leaving deposits of salt.

Liquids have different boiling points, so we can separate two liquids by boiling one of them. When we boil a liquid, it transforms in vapour. Distillation consists in collect the vapour and cool it down to liquid state again. For example, ethanol boils about 78 ºC and water boils at 100 ºC. We can separate a mixture of water and ethanol by heating it at 78 ºC. Ethanol will transform into vapour but water will stay in the recipient. Then we can drive the vapour into another recipient and collect and cool it down there.

DISTILLATION

Paula Miñana Hurtado

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